Chicago police are investigating a tip that on the night Empire actor Jussie Smollett reported being attacked by two masked men he was in an elevator of his apartment building with two brothers later arrested and released from custody in the probe.

WATCH BELOW: Chicago police want to speak with Jussie Smollett in wake of allegations he set up reported attack

Department spokesman Anthony Guglielmi says the person who lives in the building or was visiting someone there reported seeing the three together the night last month that Smollett says two masked men hurled racial and homophobic slurs at him, beat him and looped a rope around his neck.

ABC News reports that the FBI and the US Postal Inspection Service are currently investigating whether Smollett took part in sending a threatening letter addressed to him at Empire’s Chicago studio prior to the alleged attack.

Last week, police announced that the “investigation had shifted” following interviews with the brothers and their release from custody without charges. Police have requested another interview with Smollett.